So totally better than you and then some. The best of everything and everyone. So much better than you, your mom, and your dog. Better than 1337, more than 1337, overly 1337, so 1337 it's painful. The best of all and everything and you and your dog.
Contraction of über (also, though incorrectly, known as uber) and 1337.
That guy is über 1337; no one can beat him!
It means teh b3s7 of t3h 1337!
i iz Über 1337 u nub! ill pwn j00!